1. Field of the Invention
The present invention relates to a high speed photographic printer, and more specifically to a photographic control device for scanner and exposure control system calibration in a photograhic printer. It includes automatic algorithm printing matrix modification by regression analysis of prints made through the control filters when they are positioned at the scan aperture.
2. Description of the Prior Art
In the photofinishing industry, it is common practice to splice, end-to-end, many individual film strips, the negatives from many customers' cameras. The spliced film strips are wound or spooled on a relatively sizable reel and placed on a photographic printer for automatic or semi automatic projection and printing of each negative on a continuous roll of photosensitive photographic print material.
For calibration of the scanner and exposure control system in such printers, the prior art was effectively a linear transportation of control material through the printer for both scanner calibration and printer control. Later, the function of scanner calibration was accomplished by placing known density material on a solenoid and pulling or rotating this material in and out of the light path which was used to scan negatives. This data was then used to optimize the scanner by providing appropriate offsets which represented variations in scanning systems. These offsets were subsequently used to measure true relative variance in customer negatives, which allowed for automatic printing. The paper variables were calculated based on densitometer differences of a series of uniquely exposed patches printed at default values. The density values obtained after processing were evaluated and appropriate corrections were input manually to compensate for speed and color response variations within emulsions.